FIG. 1 shows a typical example of an ATM multiplexer (1). The multiplexer joins different streams, such as video, voice and data, into a single ATM link (2). The ATM link transmits ATM cells, each cell containing 53 bytes—5 bytes for a header (3) that manages the routing of the cell, and 48 bytes for payload data (4). ATM was designed for constructing low-delay packet-switching links to give high performance bandwidth.
The ATM system offers functions for different applications. The system can be divided into layers (compare to the OSI layer model). Above the ATM layer, which handles, for example, the multiplexing and demultiplexing functions, is the ATM adaptation layer (AAL) that handles convergence, segmentation, and reassembly matters. It can be said that the AAL provides for the mapping of higher-layer protocol data units (PDUs) into the payload fields of ATM cells and the reassembly of these PDUs. Several AAL protocols exist that support different applications. One of these protocols is AAL 2.
AAL 2 is especially designed for bandwidth efficient transmission, for low-rate, short length packets in delay sensitive applications. For example, compressed voice as generated in mobile networks is such an application.
It is difficult, in certain implementation, to achieve good performance for a system. If requirements for a system are low-delay connections when there are few incoming links in asynchrony, but still connection establishment rates are high, it is difficult to find a peak allocation in a way that the ATM link performance is efficient. Either the performance tends to be low in these kinds of implementations, or the algorithms are too slow for real-time fast calculation. The goal of the invention is to solve the problem of the above-mentioned implementations. This is achieved in a way described in the claims.